1. Field of the Invention
The present invention relates to a wet electrographic printer and, more particularly, to a developer supplying apparatus of a wet electrographic printer capable of controlling the concentration and level of the developer.
2. Description of the Related Art
In general, the wet electrographic printer is an apparatus for developing an electrostatic latent image formed on a photosensitive medium such as a photosensitive belt with a developer of a predetermined color and transferring the developed image to print a desired image on a paper sheet. The wet electrographic printer includes a developing unit for developing an image by supplying the developer to the photosensitive medium, and a developer supplying apparatus for constantly supplying the developer of a predetermined concentration to the developing unit. The developer is a mixture of concentrated ink containing a powder type toner and a liquid carrier, in which the toner is diluted to approximately 2.about.4 wt %. Hereinafter, the concentration of the developer is defined by the wt % of toner.
Meanwhile, the developer supplying apparatus includes an ink cartridge for storing condensed ink, a carrier cartridge for storing a liquid carrier, and a reservoir for storing the developer containing the condensed ink and the liquid carrier in a predetermined ratio. Also, agitators for preventing settling a toner of the solution may be installed in the ink cartridge and the reservoir, respectively.
In the developer supplying apparatus, the amount of developer stored in the reservoir is reduced by an amount used to develop the electrostatic latent image of the photosensitive medium, so that the condensed ink and the liquid carrier must be supplied to the reservoir to maintain the concentration of the developer at a constant concentration. Also, the level of developer stored in the reservoir must remain constant.
Also, the consumption of the toner and the liquid carrier may be different according to a printed image. That is, more liquid carrier than toner is required to print a simple image or a small image, and more toner than liquid carrier is required to print a complicated image. Thus, in order to maintain the concentration of the developer at a predetermined concentration, it is necessary to appropriately supply the toner and the developer to the reservoir in accordance with the consumption of the toner and the liquid carrier.
The developer supplying apparatus cannot control both the concentration of the developer stored in the reservoir and the level thereof. That is, if a lot of the liquid carrier is supplied to maintain the concentration of the developer in the reservoir at a predetermined level, the level of the developer may be changed and thus undesired operating conditions may be generated, or if the level of the developer is controlled, the concentration of the developer cannot be appropriately controlled.